A new generation of optoelectronic devices such as organic photovoltaic (OPV) devices, organic light emitting transistors (OLETs), organic light emitting diodes (OLEDs), organic thin film transistors (OTFTs), printable circuits, electrochemical capacitors, and sensors are built upon organic semiconductors as their active components. To enable high device efficiencies such as large charge carrier mobilities (μ) needed for transistor/circuit operations, or efficient exciton formation/splitting that is necessary for OLED/OPV operations, it is desirable that both p-type and n-type organic semiconductor materials are available. Furthermore, these organic semiconductor-based devices should exhibit satisfactory stability in ambient conditions and should be processable in a cost-effective manner. For example, a benchmark polymer, regioregular poly(3-hexylthiophene) (rr-P3HT), can provide hole mobilities of about 0.1 cm2/Vs and current modulation of about 105 or greater, which is close to amorphous silicon. For OPV devices based on rr-P3HT, power conversion efficiencies (PCEs) as high as about 4% have been reported. However, such impressive performances are achieved only under strict device processing conditions.
Accordingly, the art desires new organic semiconductor materials, particularly those that can have good charge transport characteristics, tunable energy level, processing properties, and stability in ambient conditions.